1. Field of the Art
The present invention relates in general to a method and an apparatus for recording information on a magnetic disk, and more particularly to such information recording technology wherein the recording is effected by use of a simple single-gap magnetic head, in desired data storage track sectors which are selected with sector identification data recorded on the magnetic disk.
2. Related Art Statement
In a magnetic recording apparatus for writing or recording information on magnetic recording media in the form of a magnetic disk such as floppy or hard disks, it is difficult to position the magnetic head in exact alignment with the centerline of a selected track of the magnetic disk. More specifically, the accuracy of positioning of the magnetic head relative to the magnetic disk is inevitably affected by thermal expansion and contraction of the mangetic disk, variations in concentricity of the tracks due to interchanging of disks and other factors, as well as by a positioning error of the magnetic head. Failure to establish exact alignment of the magnetic head with respect to the selected track will cause incomplete erasure of the information previously recorded on the selected track. Namely, the prior information signals are partially left as remnants adjacent to the newly recorded band. In this event, the remnant information signals are read out together with the newly recorded information signals. Such inconveniences become more and more serious as the track density and the size of the magnetic disk are increased.
To assure precise positioning of the magnetic head relative to the magnetic disk, it is known to use a magnetic head arrangement which has two additional C-shaped cores each equipped with a coil wound thereon, in addition to a read/write core. These two additional cores are spaced from each other in a radial direction of the magnetic disk, and a difference in output of the respective coils is utilized to position the magnetic head with respect to the centerline of the selected track. An example of a magnetic recording apparatus using such a magnetic head arrangement is disclosed in Japanese Patent Application which was published in 1974 under Publication No. 49-30730. This type of apparatus permits exact alignment of the magnetic head with the selected track of the magnetic disk. However, the apparatus is complicated in the construction of the magnetic head, and in the control device for positioning the magnetic head. Thus, the known apparatus indicated above is disadvantageous for its comparatively high cost of manufacture.
In the meantime, another apparatus is known in which the magnetic head is offset a predetermined distance from the centerline of a selected track of the magnetic disk in opposite radial directions of the disk, so that the information previously recorded on the selected track is erased before new information is written. In this case, the previously recorded information is erased over a width which is sufficiently greater than a width of a newly recorded band. Consequently, all the remnants of the prior information signals may be completely erased. Japanese Patent Application laid open in 1983 under Laid-Open No. 58-97104 discloses such an apparatus. In this arrangement, the complete erasure of the prior information signals makes it unnecessary to establish extremely high accuracy of relative positioning between the magnetic head and the selected track of the magnetic disk. Accordingly, the construction of the magnetic head and the control system for positioning the magnetic head may be simplified. However, this advantage is offered at the sacrifice of a disadvantage that the so-called "soft sector" system is not available. Described in more detail, information storage format data in each track, such as an ID field representing sector numbers and lengths of information recorded in a given sector, will be erased since and when the previously recorded information signals are erased completely.